(1) Field of the Invention
This invention relates to a label tape, suitable for application to vulcanizable articles to provide identification of said articles after vulcanization has been completed.
(2) Description of the Prior Art
Various techniques for identifying vulcanized articles such as vehicle tires have previously been disclosed. U.S. Pat. No. 2,984,596 (Franer) discloses a label tape providing visible indicia capable of being applied to a vehicle tire prior to vulcanization. In addition to such visible methods, magnetic identification methods have been long sought. For example, in U.S. Pat. Nos. 2,920,674 (Bull) and 3,460,119 (Ugo et al.), systems are disclosed in which the bead wires conventionally present in vehicle tires are selectively magnetized to provide an identification code. In U.S. Pat. Nos. 3,225,810 (Enabnit) and 3,233,645 (Newell), articles are disclosed wherein discrete blocks of a permanent magnet material such as barium ferrite are selectively positioned within the tire to provide an identification code. Since the discrete blocks must be positioned prior to vulcanization, the recorded information cannot be changed subsequent to vulcanization.
U.S. Pat. No. 3,750,120 (McCarty) discloses an identification system wherein a magnetic pigment such as magnetite is uniformly dispersed throughout a portion of the article such as a band on the sidewall of the tire. While this system overcomes several limitations inherent in the above discussed systems, the special compounding and other problems limit the applicability of such a system.